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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. typedef long long ll;
  4.  
  5. int main() {
  6.     ll n, k;
  7.     cin >> n >> k;
  8.     vector<ll> a(n + 1), prefix(n + 1);
  9.     for (ll i = 1; i <= n; i++){
  10.     	cin >> a[i];
  11.     	prefix[i] = prefix[i-1] + a[i];
  12.     }
  13.  
  14.     unordered_map<ll, ll> freq;
  15.     freq[0] = 1; ll c = 0;
  16.  
  17.     for (ll j = 1; j <= n; j++) {
  18.         ll y = ( (prefix[j] % k - j % k + k) % k );
  19.         if(freq.find(y)!=freq.end()){
  20. 			c = c + freq[y];
  21. 		}
  22.  
  23.         freq[y]++;
  24.     }
  25.     cout << c << "\n";
  26. }
Success #stdin #stdout 0s 5304KB
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stdin
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5 2
2 2 2 2 2
stdout
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6
https://ideone.com/aKsCHZ
language:
C++14 (gcc 8.3)
created:
1 day ago
visibility:
public

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